Immunisation of the somatostatin gene alters hypothalamic-pituitary-liver gene expressions and enhances growth in Dazu black goats.

Objective: Somatostatin (SS) plays important regulatory roles in animal growth and reproduction by affecting the synthesis and secretion of growth hormone (GH). However, the mechanism by which SS regulates growth and development in goats is still unclear. Methods: In this study, we randomly selected eight 7monthold Dazu black goats (DBGs) of similar body weight and equally assigned four bucks as the immunised and negative control groups. The immunised group received the Salmonella typhi attenuated vaccine X9241 (ptCS/2SSasd) orally, whilst the negative control group received the empty vector vaccine X9241 (pVAXasd) orally. Results: The SS concentration in the serum of goats in the immunised group was significantly lower than that in the negative control group, and the daily gain was significantly higher (p<0.05). SS14 DNA vaccine immunisation resulted in significantly higher concentrations of growthrelated hormones such as GHreleasing hormone and insulin growth factor 1 (IGF1) in the serum of goats (p<0.05). RNAseq analysis of hypothalamus of oral SS14 DNA vaccine and negative control DBGs identified 31 differentially expressed genes (DEGs). Pituitary gland identified 164 DEGs. A total of 246 DEGs were detected in the liver by RNAseq. Gene ontology of DEGs was enriched in mitochondrial envelope, extracellular region, receptor binding and cell proliferation. The biological metabolic pathways associated with DEGs were explored by Kyoto encyclopedia of genes and genomes analysis. DEGs were associated with metabolic pathways, oxidative phosphorylation, vitamin digestion and absorption and galactose metabolism. These candidate genes (e.g. DGKK, CYTB, DUSP1, and LRAT) may provide references for exploring the molecular mechanisms by which SS promotes growth and development. Conclusion: Overall, these results demonstrated that the SS DNA vaccine enhanced the growth of DBGs by altering growthrelated hormone concentrations and regulating the expression of growthrelated genes in the hypothalamic--pituitary--liver axis. [ABSTRACT FROM AUTHOR]